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1 December 2007 Social Encounters Between Male Brown Spiders, Loxosceles gaucho (Araneae, Sicariidae)
André Augusto Stropa
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Twenty-two interactions between males of Loxosceles gaucho Gertsch 1967 were investigated in order to study its intrasexual interactions and level of aggressiveness. Aggression by lunges or bites was observed in just 22.7% of the trials and three behaviors were identified as aggression-attenuating mechanisms: a hug; fleeing, and a postural pattern (POS). Interactions took place in 59.1% of the trials and the pairs interacted using one or two behavioral patterns (vibratory and/or postural). The vibratory pattern (VIB) consisted of foreleg vibration, palpal drumming, and abdominal pulsation and was used by both resident and intruder opponents. The postural pattern (POS) was used exclusively by resident males and it was similar to the behavioral pattern of sexually receptive L. gaucho females; in these cases the intruder male responded using the VIB. In conclusion, the interaction between adult L. gaucho males is usually non-aggressive. The behaviors described in this study possibly promote group-living and help to explain the gregarious populations of recluse spiders. Intra-specific sexual mimicry can occur in these interactions, but this hypothesis requires further investigation.

André Augusto Stropa "Social Encounters Between Male Brown Spiders, Loxosceles gaucho (Araneae, Sicariidae)," The Journal of Arachnology 35(3), 493-498, (1 December 2007).
Received: 26 July 2006; Published: 1 December 2007

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